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Project IceSARAndrew BrownfieldCameron Chapman
Nicholas MansJon Wehling
ObjectiveBuild and test a Synthetic Aperture Endfire Array Radar in order to reconstruct 3D image of the terrain in front of the spacecraft.
Enceladus (moon of Saturn)Mean radius 252.1 ± 0.1 km (0.0395
Earths)[7]
Mass(1.080 22 ± 0.001 01) × 1020 kg[7] (1.8×10-5 Earths)
Surface temp. Kelvin[10]
Average: 75KMax: 145K
Subterranean Oceans
Fissures Ice Geysers
Project VALKYRIE
NASA’s Request For Proposals
VALKYRIE – collaborations between Stone Aerospace and Professor Gasiewski
Request for prototype to Antarctica
From there the design goes to Enceladus
(Very-Deep Autonomous Laser-Powered Kilowatt-Class Yo-Yoing Robotic Ice Explorer)
VALKALRIE’s obstacle avoidance
Radar driven obstacle avoidance• Use radar to see rocks through ice
– 500MHz needed• Space issues
– Patch or dipole antenna
Patch Antenna Radiation Dipole Antenna Radiation
Accurate object detection requires sufficient resolution, either through a scanning focused beam or by utilizing SAR to synthetically narrow the beam
Synthetic Aperture Radar (SAR)
http://www.rfcafe.com/references/electrical/NEETS%20Modules/NEETS-Module-11-3-1-3-10.htm
• Using the Range Gating Principle it is possible to calculate the distance to an object
• The magnitude and phase of the return signal at multiple positions allows for the reconstruction of a radar image and relative position of the object in 3D space
Synthetic Aperture Radar (cont.)• A single broad radar pulse will provide general distance information, but
no direction, due to azimuthal ambiguity• Multiple pulses from different locations provide a tool for determining
direction, thus effectively narrowing the beam width• By sampling many times in a flyby plane or satellite, one can sweep out
large tracts of information, with each point on the ground generated with many different radar pulses.
www.skylondaworks.com/sc_sar0.htm
VALKYRIE’s SAR• Probe moves towards the objects it’s
detecting, not orthogonal to it• Complex algorithms to determine
relative position of an object• 4 antennae are not pointed
orthogonally or parallel, but tilted and concentrically oriented around the nose of the probe
High Level Systems Layout
Solid Objects
Power Management
System
Patch/ Dipole Antenna Array
Transceiver Pulse/Signal Generator Receiver
Signal Processing and Correction
Data Processing (Matlab) SAR Image
Microwave Isolators
Transmitter
• 100W transmission power– Sin wave generator (500MHz)– 30ns Pulse (gated switch)– Amplifier
Antenna
Dipole• Omnidirectional Radiation• Compact• Backplane λ/4 separation to
partially direct the beam
Microstrip patch• Hemispherical radiation• Backplane next to patch• Each patch must be λ/2 in
length
Receiver
• Receive a radar pulse with 2km pathlength• Isolator (Protection against transmitter
feedback)• Magnitude and Phase
Computer Interface and Control
• FPGA Altera board NIOS II core– Monitor power– Control Radar pulse width and Range-gating of
received signals
• National Instruments Data Acquisition (DAQ) PCI board. – Desktop interface and file storage for post
processing
Software
Post Process• Matlab image processing of
CSV file.• SAR algorithm processing to
reduces azimuthal ambiguity in radar
Interface• Altera development
software• NI board software• C based GUI
Power
• Bench-top devices• Regulated DC for FPGA• Power through the National Instruments card.
Division of Labor
• Cameron-FPGA Programming• Jon-Signal Processing• Andrew-Antenna Design• Nick-Hardware Integration and Testing
Preliminary Schedule• Highly Modular• Plan on having hardware completed by Milestone
1
Risks and Contingency
• Learning curve - Relatively inexperienced with antennas/radar
• NTIA regulations - frequency control• Broadcast around 500MHz (Transparent
frequency of Ice)• High Cost - Much covered by Stone Aerospace• Build vs. Buy• Time - Complex integration/ functional testing
BudgetComponent Estimated Cost
Receiver Unknown
Transmitter Unknown
FPGA $80
Antennae $100
NI interface card $500
PCB $100
Misc Parts $100
Power $50
Total $1000+
FIN
• Questions?